Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for ITU-T Y.1731 Performance Monitoring in a Service Provider Network

IEEE-compliant connectivity fault management (CFM) must be configured and enabled for Y.1731 performance monitoring to function.

Information About ITU-T Y.1731 Performance Monitoring in a Service Provider Network

Frame Delay and Frame-Delay
Variation

The Frame Delay
parameter can be used for on-demand OAM measurements of frame delay and
frame-delay variation. When a maintenance end point (MEP) is enabled to
generate frames with frame-delay measurement (ETH-DM) information, it
periodically sends frames with ETH-DM information to its peer MEP in the same
maintenance entity. Peer MEPs perform frame-delay and frame-delay variation
measurements through this periodic exchange during the diagnostic interval.

An MEP requires the
following specific configuration information to support ETH-DM:

MEG level—MEG
level at which the MEP exists

Priority

Drop
eligibility—marked drop ineligible

Transmission rate

Total interval of
ETH-DM

MEF10 frame-delay
variation algorithm

A MEP transmits
frames with ETH-DM information using the TxTimeStampf information element.
TxTimeStampf is the time stamp for when the ETH-DM frame was sent. A receiving
MEP can compare the TxTimeStampf value with the RxTimef value, which is the
time the ETH-DM frame was received, and calculate one-way delay using the
formula
frame delay =
RxTimef – TxTimeStampf.

One-way frame-delay
measurement (1DM) requires that clocks at both the transmitting MEP and the
receiving MEPs are synchronized. Measuring frame-delay variation does not
require clock synchronization and the variation can be measured using 1DM or a
frame-delay measurement message (DMM) and a frame-delay measurement reply (DMR)
frame combination.

If it is not
practical to have clocks synchronized, only two-way frame-delay measurements
can be made. In this case, the MEP transmits a frame containing ETH-DM request
information and the TxTimeStampf element, and the receiving MEP responds with a
frame containing ETH-DM reply information and the TxTimeStampf valued copied
from the ETH-DM request information.

Two-way frame delay
is calculated as
frame delay =
RxTimeb – TxTimeStampf, where RxTimeb is the time that the frame with
ETH-DM reply information was received. Two-way frame delay and variation can be
measured using only DMM and DMR frames.

To allow more precise
two-way frame-delay measurement, the MEP replying to a frame with ETH-DM
request information can also include two additional time stamps in the ETH-DM
reply information:

RxTimeStampf—Time
stamp of the time at which the frame with ETH-DM request information was
received.

TxTimeStampb—Time
stamp of the time at which the transmitting frame with ETH-DM reply information
was sent.

Note

Discard frame-delay
and frame-delay variation measurements for continuity and availability faults
or when known network topology changes occur.

An MIP is transparent
to the frames with ETH-DM information; therefore, a MIP does not require
information to support the ETH-DM function.

The figure below
shows a functional overview of a typical network in which Y.1731 performance
monitoring is used.

How to Configure ITU-T Y.1731 Performance Monitoring in a Service Provider Network

Configuring Performance
Monitoring Parameters

The following new
commands were introduced that can be used to configure and display performance
monitoring parameters:
debugethernetcfmpm,
monitorlosscounters, and
showethernetcfmpm.

For more information
about CFM and Y.1731 performance monitoring commands, see the
Cisco IOS Carrier
Ethernet Command Reference. For more information about debug commands, see
the
Cisco IOS Debug
Command Reference.

MIBs

RFCs

RFC

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

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Technical Assistance

Description

Link

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Feature Information for ITU-T Y.1731 Performance Monitoring in a Service Provider Network

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.